Stents have found significant utility for facilitating the opening of clogged or narrowed vessels, such that the flow of blood or other biological fluid is restricted. In addition to blood vessels, stents have found utility for use in bile ducts, ducts of the reproductive system, and other similar vessels in the body. Of particular medical importance are coronary stents, which are placed in a coronary artery or other arteries to treat atheroscerosis. Stents used to open vessels generally have an elongate cylindrical structure with stent walls having an open construction that provides for tissue in growth around the stent frame. The stents are delivered in a low profile configuration and are extended out to the vessel within the patient either simultaneously or subsequently to a procedure to correspondingly expand the diameter of the vessel lumen. However, stents can be prone to restenosis, due to an inflammatory response induced by the foreign object in the body. In other words, in some cases thrombus formation or the like can take place at the site of the stent.
To reduce restenosis, polymer coatings have been used to coat stents, and the coatings generally are drug eluting. The coatings generally comprise a hydrophilic polymer that is coated over the frame elements. The coated stents maintain an open structure of the frame. Coated stents have met with considerable success commercially. However, studies have suggested cracking of the polymer coating that has been linked in studies with deleterious effects to the patient.